I was outside sweeping the sidewalk today, and swept an ant out into the street. “Aw, the poor feller will never find his way home again,” I thought, and then suddenly remembered why I thought he’d be lost forever.
It came from a book I read when I was a kid. Its title was something along the lines of “Upon a Sidewalk,” IIRC. In the story, the ant protagonist is somehow swept away from his scent trail, and spends the rest of the story exploring the terrain and trying to find it, because unless he does, he’ll never find his way back to his nest.
I vaguely remember the story as containing more facts about ants, so it was probably one of those education-in-disguise books of which my mother was so fond. Consequently, I’m wondering if it’s true that ants are lost without a scent trail. (Did I condemn the ant to wandering the pavement for the rest of his short life?)
Essentially true. Ants mostly navigate by the scent trails they leave behind. You can disrupt a column easily by washing away the scent trail. The ants will scurry around franticly until they bump into the scent trail and eventually re-establish it.
Richard Feynman observed things, including ants. Here’s one story:
“In my room at Princeton I had a bay window with a U-shaped windowsill. One day some ants came out on the windowsill and wandered around a little bit. I got curious as to how they found things. I wondered, how do they know where to go? Can they tell each other where food is, like bees can? Do they have any sense of geometry?
This is all amateurish; everybody knows the answer, but I didn’t know the answer, so the first thing I did was to stretch some string across the U of the bay window and hang a piece of folded cardboard with sugar on it from the string. The idea of this was to isolate the sugar from the ants, so they wouldn’t find it accidentally. I wanted to have everything under control.
Next I made a lot of little strips of paper and put a fold in them, so I could pick up ants and ferry them from one place to another. I put the folded strips of paper in two places:
Some were by the sugar (hanging from the string), and the others were near the ants in a particular location. I sat there all afternoon, reading and watching, until an ant happened to walk onto one of my little paper ferries. Then I took him over to the sugar. After a few ants had been ferried over to the sugar, one of them accidentally walked onto one of the ferries nearby, and I carried him back.
I wanted to see how long it would take the other ants to get the message to go to the “ferry terminal.” It started slowly but rapidly increased until I was going mad ferrying the ants back and forth.”
Wouldn’t the ant scurry around until it found somebody’s scent trail? Will they only return to their original nest? If they went to a foreign nest, would they be assimilated or shunned or worse?
I always worry a little about flies that get caught in the car on the highway and get let out many miles away. Do they care? Can they easily figure life out again?
Your ant will probably find his way home just fine. Ants rely on scent trails to lead the to food, they aren’t in any way reliant on scent rails them to get back home again.
If that were the case then every time it rained every ant that was outside the nest would die since all scent trails are immediately washed away.
Just as importantly forgaing ants explore by means of a random walk. If ants relied on scent trials to get back home then every time an ant found a food source after 3 hours foraging she would need to take the same meandering 3 hour path back home. And then the rest of the colony would need to take the same 6 hour round trip to the food source, even though it is only a few yards from the nest.
Neither of those effects is conductive to survival and needless to say ants don’t use them.
Instead ants use a variety of visual cues to see which way home is. Ants may not be able to see very well, but they can detect light and dar and they can detect the polarisation of light meaning they have a built-in direction finder. Combine those two senses with some software direction processors and ants can make a bee-line for home fom anywhere they walk.
That allows foraging ants that discover a food source to go straight home, laying down a scent trail as it returns. The other ants can then follow that scent trail to the food in an approximately straight line. It also allows ants that are a caught out in the rain to get home just fine.
As the link above shows, an ant that is moved can have some trouble using those cues correctly, but they generally have a good enough spatial map to allow them to get close to the nest and then wander a round until they find it. Just how far they can be moved and still find home I don’t know but simply sweeping an ant out the door isn’t going to have much effect unless it’s a huge building.